Summary: A Modular Hierarchy of Logical Frameworks
Robin Adams
University of Manchester
robin.adams@ma.man.ac.uk
Abstract. We present a method for defining logical frameworks as a
collection of features which are defined and behave independently of one
another. Each feature is a set of grammar clauses and rules of deduction
such that the result of adding the feature to a framework is a conservative
extension of the framework itself. We show how several existing logical
frameworks can be so built, and how several much weaker frameworks
defined in this manner are adequate for expressing a wide variety of
object logics.
1 Introduction
Logical frameworks were invented because there were a large number of di#ering
systems of logic, with no common language or environment for their investigation
and implementation. However, we now find ourselves in the same situation with
the frameworks themselves. There are many systems that are used as logical
frameworks, and it is often di#cult to compare them or share results between
them. It is often much work to discover whether two frameworks can express the
same class of object logics, or whether one is stronger or weaker than the other. If